Papa Bob's Mega Solution Part 5 - Adding Enums

Tutorial Series: Free C# Fundamentals via ASP.NET Web Apps

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This is the fifth part of the solution for Papa Bob's Mega Challenge. In this part, we are going to create enumerations to represent different properties being passed through the solution.

Step 1: Creating Enum Values

In order to avoid the use of "magic strings" in our code, as well as to make the project more easily modified in the future, we'll convert several of the Order properties from ints to enums. Specifically, the Crust, Size and PaymentType integers. If you recall from previous lessons, enums have an implicit zero-based integer value by which they're referenced. Because of this, we can take an integer value, such as Crust, and match it with an Enum.

To begin, add a new folder called 'Enums' to the 'PapaBobs.DTO' by selecting it in the Server Explorer and clicking Add > New Folder:


cs-asp-070---papabobsmegachallenge-part5-001


Next, add three new classes with the following names to this folder by right-clicking and selecting: Add > New Item:


cs-asp-070---papabobsmegachallenge-part5-002


Next, open the CrustType class and change it from a class to a public enum. Populate it with the following types:


cs-asp-070---papabobsmegachallenge-part5-003


Tip:

These sizes will be implicitly assigned an integer value. Therefore, this declaration is equivalent to the following assignment:


cs-asp-070---papabobsmegachallenge-part5-004


For the sake of simplicity, we will leave these assignments implicit in this project. However, if for some reason in the future they needed to be overridden (such as the case of adding a stuffed crust), the code only needs to be changed in the enum, not in every reference throughout the program.

Next, go to the other two classes and make the following changes to change them to enums:


cs-asp-070---papabobsmegachallenge-part5-005



cs-asp-070---papabobsmegachallenge-part5-006


Step 2: Converting int Properties to Enums

Now that the enums have been created, the appropriate properties can be assigned to them from within the Entity Data Model. Navigate to PapaBobsEntities within the Persistence layer to begin. Next, right-click on the Size property in the Order diagram and select 'Convert to Enum':


cs-asp-070---papabobsmegachallenge-part5-007


In the resulting dialog, set the Enum Type Name to 'SizeType'. Check the box at the bottom that says 'reference external type' and reference the SizeType Enum in the DTO class:


cs-asp-070---papabobsmegachallenge-part5-008


Tip:

What the compiler is doing behind the scenes is worth noting. This Order diagram is derived of information actually stored in the Order class that was generated from our Orders table. When a property, such as this enum conversion, is changed in the diagram, it is reflected in that Order class:


cs-asp-070---papabobsmegachallenge-part5-009


Next, make the same conversion to the two other properties, referencing the appropriate enum:


cs-asp-070---papabobsmegachallenge-part5-010



cs-asp-070---papabobsmegachallenge-part5-011


Now, save all the projects in your solution to commit these changes. A dialog window may appear stating that external changes have been made to your properties, and asks if you'd like to reload them. Select 'Yes to All'.

These changes need to be reflected also in the OrderDTO class. Copy and paste the updated properties of the Order class into the OrderDTO class, replacing its previous properties:


cs-asp-070---papabobsmegachallenge-part5-012


Step 3: Altering the orderDTO

Return now to the Default.aspx.cs page where we create the orderDTO. Notice that, in our hard-coded test, the Size, Crust and PaymentType properties are still set to integer values:


cs-asp-070---papabobsmegachallenge-part5-012


The problem with this is that the OrderDTO is now expecting an enum value to be supplied for these values, causing the compiler to give the following error:


cs-asp-070---papabobsmegachallenge-part5-013


We can resolve this issue by substituting enum values for these integers:


cs-asp-070---papabobsmegachallenge-part5-014


Save and run the project, then click on the Order button to see that the results are still saved successfully into the database:


cs-asp-070---papabobsmegachallenge-part5-015

Conclusion:

This concludes this part of the solution for the challenge. In the next part, we'll take the user-supplied values and create an order using that information.



Related Articles in this Tutorial:

Lesson 1 - Series Introduction

Lesson 2 - Installing Visual Studio 2015

Lesson 3 - Building Your First Web App

Lesson 4 - Understanding What You Just Did

Lesson 5 - Working with Projects in Visual Studio

Lesson 6 - Simple Web Page Formatting in Visual Studio

Challenge 1

Solution 1

Lesson 7 - Variables and Data Types

Lesson 8 - Data Type Conversion

Lesson 9 - Arithmetic Operators

Lesson 10 - C# Syntax Basics

Challenge 2 - ChallengeSimpleCalculator

Solution - ChallengeSimpleCalculator

Lesson 11 - Conditional If Statements

Lesson 12 - The Conditional Ternary Operator

Challenge 3 - ChallengeConditionalRadioButton

Solution - Challenge Conditional RadioButton

Lesson 13 - Comparison and Logical Operators

Lesson 13 Challenge - First Papa Bob's Website

Solution - Challenge First Papa Bob's Website

Lesson 14 - Working with Dates and Times

Lesson 15 - Working With Spans of Time

Lesson 16 - Working with the Calendar Server Control

Challenge 4 - Challenge Days Between Dates

Solution - Challenge Days Between Dates

Lesson 17 - Page_Load and Page.IsPostBack

Lesson 18 - Setting a Break Point and Debugging

Lesson 19 - Formatting Strings

Challenge 5 - Challenge Epic Spies Assignment

Solution - Challenge Epic Spies Assignment

Lesson 20 - Maintaining State with ViewState

Lesson 21 - Storing Values in Arrays

Lesson 22 - Understanding Multidimensional Arrays

Lesson 23 - Changing the Length of an Array

Challenge 6 - Challenge Epic Spies Asset Tracker

Solution - Challenge Epic Spies Asset Tracker

Lesson 24 - Understanding Variable Scope

Lesson 25 - Code Blocks and Nested If Statements

Lesson 26 - Looping with the For Iteration Statement

Challenge 7 - Challenge For Xmen Battle Count

Solution - Challenge For Xmen Battle Count

Lesson 27 - Looping with the while() & do...while() Iteration Statements

Lesson 28 - Creating and Calling Simple Helper Methods

Lesson 29 - Creating Methods with Input Parameters

Lesson 30 - Returning Values from Methods

Lesson 31 - Creating Overloaded Methods

Lesson 32 - Creating Optional Parameters

Lesson 33 - Creating Names Parameters

Lesson 34 - Creating Methods with Output Parameters

Challenge 8 - Challenge Postal Calculator Helper Methods

Solution - Challenge Postal Calculator Helper Methods

Mega Challenge Casino

Solution - Mega Challenge Casino

Lesson 35 - Manipulating Strings

Challenge 9 - Phun With Strings

Solution - Challenge Phun With Strings

Lesson 36 - Introduction to Classes and Objects

Challenge - Hero Monster Classes Part 1

Solution - Hero Monster Classes Part 1

Challenge - Hero Monster Classes Part 2

Solution - Challenge Hero Monster Classes Part 2

Lesson 37 - Creating Class Files Creating Cohesive Classes and Code Navigation

Lesson 38 - Understanding Object References and Object Lifetime

Lesson 39 - Understanding the .NET Framework and Compilation

Lesson 40 - Namespaces and Using Directives

Lesson 41 - Creating Class Libraries and Adding References to Assemblies

Lesson 42 - Accessibility Modifiers, Fields and Properties

Lesson 43 - Creating Constructor Methods

Lesson 44 - Naming Conventions for Identifiers

Lesson 45 - Static vs Instance Members

Challenge 10 - Challenge Simple Darts

Solution - Challenge Simple Darts

Lesson 46 - Working with the List Collection

Lesson 47 - Object Initializers

Lesson 48 - Collection Initializers

Lesson 49 - Working with the Dictionary Collection

Lesson 50 - Looping with the foreach Iteration Statement

Lesson 51 - Implicitly-Typed Variables with the var Keyword

Challenge 11 - Challenge Student Courses

Solution - Challenge Student Courses

Mega Challenge War

Solution - Mega Challenge War

Lesson 52 - Creating GUIDs

Lesson 53 - Working with Enumerations

Lesson 54 - Understanding the switch() Statement

Lesson 55 - First Pass at the Separation of Concerns Principle

Lesson 56 - Understanding Exception Handling

Lesson 57 - Understanding Global Exception Handling

Lesson 58 - Understanding Custom Exceptions

Lesson 59 - Creating a Database in Visual Studio

Lesson 60 - Creating an Entity Data Model

Lesson 61 - Displaying the DbSet Result in an ASP.NET GridView

Lesson 62 - Implementing a Button Command in a GridView

Lesson 63 - Using a Tools-Centric Approach to Building a Database Application

Lesson 64 - Using a Maintenance-Driven Approach to Building a Database Application

Lesson 65 - Creating a New Instance of an Entity and Persisting it to the Database

Lesson 66 - Package Management with NuGet

Lesson 67 - NuGet No-Commit Workflow

Lesson 68 - Introduction the Twitter Bootstrap CSS Framework

Lesson 69 - Mapping Enum Types to Entity Properties in the Framework Designer

Lesson 70 - Deploying the App to Microsoft Azure Web Services Web Apps

Papa Bob's Mega Challenge

Papa Bob's Mega Solution Part 1 - Setting up the Solution

Papa Bob's Mega Solution Part 2 - Adding an Order to the Database

Papa Bob's Mega Solution Part 3 - Passing an Order from the Presentation Layer

Papa Bob's Mega Solution Part 4 - Creating the Order Form

Papa Bob's Mega Solution Part 5 - Adding Enums

Papa Bob's Mega Solution Part 6 - Creating an Order with Validation

Papa Bob's Mega Solution Part 7 - Calculating the Order Price

Papa Bob's Mega Solution Part 8 - Displaying the Price to the User

Papa Bob's Mega Solution Part 9 - Creating the Order Management Page


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